Synthetic Aperture Radar missions

Envisat ASAR mosaic of changes in Arctic sea-ice

Unlike optical systems that rely on reflected solar radiation or thermal radiation emitted by Earth, imaging radar instruments work independently of light and heat. Radar is an active system that transmits a beam of radiation in the microwave region of the electromagnetic spectrum.

SAR can provide day-and-night imagery of Earth. In addition, clouds, fog and precipitation do not have any significant effect on microwaves, so images can also be acquired independent of weather conditions.